If you're heading to the movies this summer, you may want to bring a life jacket. A wave of Hollywood films with nautical themes will be crashing down on theaters, starting at the end of the month.

Along with all of the sequels and superheroes, swells of seafoam will tinge the big screen courtesy of a half-dozen or so films, including Pixar's 3-D fish tale "Finding Nemo," DreamWorks' "Sinbad: Legend of the Seven Seas," and Disney's "Pirates of the Caribbean."

One reason for the tide of ocean films is the success of seafaring pictures such as "The Perfect Storm" in 2000 and "Titanic" in 1997. Another is technological advances that make it possible to leave audiences waterlogged for a fraction of the former cost. (The movies' budgets range from $60 million to $140 million, compared with $200 million for "Titanic.")

"The temptation [for studios] to rediscover this kind of storytelling is so great because the technology allows you to ... not make it look like it was filmed in a bathtub," says Robert Thompson, professor of television and popular culture at Syracuse University in New York. " 'The Perfect Storm' and 'Titanic' were the dress rehearsals for the reemergence of this type of filmmaking. They were successful and demonstrated that it could be done well."

He says the trend reflects an industry follow-the-leader approach seen almost every year. (Remember "A Bug's Life" and "Antz," or "Dante's Peak" and "Volcano"?)

Hollywood also has released more family fare over the past several years, and most of these aquatic films are aimed at children. Stories about a journey or quest into the unknown - whether it's the high seas, faraway lands, or outer space - are beautiful to look at and appealing, especially to young people, says Jim Farrelly, a professor of English at University of Dayton in Ohio. "They offer an escape. It's an outgrowth of adventure-based films, like 'Lord of the Rings.' "

But big-splash films aren't guaranteed to succeed at the box office, says Paul Dergarabedian of Exhibitor Relations in Encino, Calif. Filmmakers may find the theme to be extremely cinematic, but "the writing, acting, and marketing all have to be there," he says.

The infamous "Waterworld," which cost $175 million, lost money in the US and barely floated a profit after it was released internationally. Last year, "Treasure Planet," which combines nautical and space themes, cost $140 million and sank at the box office. And with so many ocean films debuting just weeks apart, there's a risk they could drown each other out.

So why is Hollywood pouring money into them? For one, international distribution and DVD sales can help pad any loss, says Christopher Ames, provost at Oglethorpe University in Atlanta. "The video market is huge for the children's films, which helps minimize risk."

CGI turns on the water

Filmmakers have come a long way since "Moby Dick" and "Captains Courageous." These films were shot using small tanks and boat models, Ames says.

Today, computer effects and wave and fog machines allow studios to literally control the weather. And in animated films, CGI lets artists show more water on screen than ever before, creating vivid panoramics and tiny droplets compared with the days when water scenes were laboriously hand-drawn, frame by frame, in films like "Pinocchio."

Animators for "Finding Nemo," which debuts May 30 and is about a fish's journey through the Great Barrier Reef to find his missing son, combines Pixar's high-resolution animation with 3-D. Almost every scene has water, which posed a challenge not only to make the ocean look real - but to keep the underwater coral-reef backgrounds moving with the currents, says Oren Jacob, supervising technical director for the movie.

Making "Nemo" would have been "prohibitively expensive five years ago," he says. "Today, computers are faster. We have a better understanding of the theoretical physics of water."

To accurately animate the sea, "Nemo" creators studied the behavior of water and wrote algorithms based on the physics of its movement. "We looked at how toilets flush, sprayed a garden hose up in the air, gently poured a cup of milk into a calm fish tank of water to see how it mixes," Jacob says.

Then they programmed their equations into the same software used to create Sulley's hair in "Monsters Inc." This gave artists a fine palette with which to form detailed sprays or large swells, he says, although some scenes took almost a year to perfect.

For DreamWorks, creators of the hand-drawn and computer-animated "Sinbad," debuting July 2, the line between digital and live-action films is blurring. "We see Sinbad as a great big fantasy movie - we think of it in more live-action terms. We see films like 'Spider-Man' and 'Lord of the Rings' as inspirations," says Patrick Gilmore, director for the movie.

Mr. Gilmore, who has been working on "Sinbad" for four years with a team of 600 people, says it would have been difficult to make a film with 50 percent ocean 10 years ago. "If you made a big ocean vista - you had to draw every frame of moving ocean," he says.

The film was made using software that gave artists a virtual ocean with which to more creatively convey the classic story of Sinbad, he says. It offered "an ocean with calm seas, different levels of foams ... controls that allowed us to show sunlight going through waves."

Creating the perfect storm

The live-action realm presents a whole different set of challenges to filming on water.

"Master and Commander: The Far Side of the World," starring Russell Crowe and based on the series by Patrick O'Brian, was filmed in the same multiacre, 40-feet deep horizon tank used for "Titanic" in Mexico. The tank sits on a bluff and blends in with the Pacific Ocean.

A big challenge was simulating Mother Nature. In sunny Mexico, filmmakers had to use a fog machine and water hoses attached to jet engines to create stormy conditions. Boats also sat on devices that would rock them in sync with tidal waves generated by machines, says Leon Poindexter, a shipwright who advised filmmakers about the historical design of the ships.

Creators also strove for accuracy on the main ship, which represented the early 19th-century HMS Surprise, Mr. Poindexter says. It was a French boat captured and converted to the British fleet, he says, and details reflect that era - including the rigging weaves, the cannons - even the chickens and rats on board.

But going overboard with razzle-dazzle effects can sometimes mean that dialogue and human-interest elements get lost in the storm.

"There may be more sea in seafaring films, but sometimes to the detriment of quality," Thompson says, pointing to a lack of compelling dialogue in "Titanic."

Conscious of this balancing act, "Sinbad" filmmakers hand-drew their characters, so they would appear more personal, says Gilmore.

For another oceanside-based film, "The Whale Rider," the human-interest aspect is intended to carry the story.

"With contemporary filmmaking, we are used to being thrilled or amused or excited. But very few films give you the opportunity to feel," says Niki Caro, director of "The Whale Rider." Set on New Zealand's East Coast, it's about a Maori girl and her tribe's relationship with the sea.

"It was the right time for this story.... I think that in the beginning of this millennium we are overwhelmed by technology," she adds. "We crave a connection with something. This story ... shows us a community of people who live simply, according to the laws of nature and to beliefs they have held on to for 1,000 years."

Not that much walking the planks

For their part, sailors who have spent their lives riding the ocean say filmmakers' track record at sea isn't great. A group of boatmakers and sailors from Martha's Vineyard, Mass., say that such blockbuster films have fallen short on plot development and accuracy.

"Most of these films are just overdramatized. The films would be better ... if they had an honest presentation of storms and life at sea," says Nat Benjamin, who crafts schooners and takes people on commercial sailing trips.

He points to "The Perfect Storm" as a "grossly exaggerated" example. "They are in the storm of the century fighting for their lives, and [one character's] main concern was keeping his Diet Coke from spilling," he says. He adds that he liked the 1981 German film "Das Boot" because "you felt the terror of being in a U-Boat."

Hollywood also tends to glamorize sea life and ignore the mundane side of it, says Scott DiBiaso, a commercial sailor and boatmaker who has worked on several films, including the recently completed "Pirates of the Caribbean." "It's a lot more work than people think. You prepare the food, clean, change the sails," he says. "They take the most outrageous part of seafaring and try to make it seem like everyday life.... But a film about day-to-day life - that won't sell tickets."

Another sailor, Jim Lobdell, says his ship was featured in "Message in a Bottle." When the boat tips over, it's obvious, he says, that filmmakers had to remove the lead balance because his boat wouldn't have blown over in the conditions they showed.

Mr. DiBiaso, who cites "Captains Courageous" when asked for a good sea yarn, was irked by a scene in a "The Perfect Storm," when the fishing crew cheers after surviving a large wave. "Any situation I've been in that was dangerous, the last thing I was doing was high-fiving. You are seriously humbled," he says. "You can't be arrogant [with] the sea.... When you have a 30-foot wave coming after you and it's freezing cold, it teaches you a lot of respect for nature." He adds, "You find a greater appreciation for the simple things when you do return."